Antiaging hormone fights cellular damage

A newly discovered antiaging hormone has been found to work at least in part by increasing cells' ability to detoxify harmful reactive oxygen species.

Called Klotho, the hormone is secreted in blood. A defect in the klotho gene in mice causes a syndrome closely resembling human aging. Overexpression of the gene, on the other hand, extends mouse lifespan.

In the Journal of Biological Chemistry , Makoto Kuro-o and colleagues of the University of Texas Southwestern Medical Center at Dallas have shown one way in which Klotho extends lifespan.

Using cultured cells and transgenic mice, the researchers demonstrated that Klotho increases resistance to oxidative stress.

"Increased longevity is always associated with increased resistance to oxidative stress," says Kuro-o in a news release . "Oxidative stress causes the accumulation of oxidative damage to important biological macromolecules such as DNA, lipids, and proteins that would result in functional deterioration of the cell, which eventually causes aging."

"In this study," says Kuro-o, "we propose that Klotho does its job by increasing the ability of the cell to detoxify harmful reactive oxygen species, thereby increasing resistance to oxidative stress of the body."

The protein turns on an enzyme called manganese superoxide dismutase . This enzyme, found in mitochondria in cells, hydrolyzes harmful superoxide into less harmful hydrogen peroxide.

According to the news release, Klotho research could lead to the development of antiaging drugs.

"We showed that the antiaging hormone Klotho confers resistance to oxidative stress in cells and animals," says Kuro-o. "This means that Klotho protein itself or small molecule mimetics may be potentially useful as antiaging medicines."

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